Abstract
The influence on human equilibrium of positive and negative middle ear pressure was studied with a strain gauge platform and head position sensor system. The data obtained were digitalized and analysed by a microcomputer, Deviation of head and body sway center followed by eye closure was adopted as the parameter for the analysis. Three groups of people were examined; 1) patients with unilateral otitis media with effusion (OME), 2) normal volunteers, 3) patients with middle ear ventilation tubes on one side. Patients in group 1 were examined before and after the treatment of OME. Those in groups 2 and 3 were examined with positive or negative pressure applied on the ear randomly chosen (group 2), or on the ear with a ventilation tube inserted (group 3). The OME patients' head deviation to the affected side turned to the opposite side right after treatment. Head deviation similar to that of the untreated OME patients was observed when positive external earcanal pressure (group 2) or negative middle ear pressure was applied. The shift of the stapes' foot plate might be one of the causes of these head deviations. More studies are needed to clarify the mechanisms of disequilibrium produced by unusual middle ear pressure.
